Soil microbial community of urban green infrastructures in a polar city

Urban and technogenic landscapes in subarctic zones are not considered comfortable habitats for soil microbiota. However, green infrastructures in polar cities can provide a new niche for the development of a microbial soil community. Soil microbial biomass and the diversity of cultivable microfungi have been studied in relation to the chemical and morphological properties of urban soils in the polar city of Apatity. The quantitative indicators based on fluorescence microscopy and PCR real-time methods as well as the qualitative composition of the cultivable microfungal community were used to characterize the microbial community. Changes in the morphological and chemical composition of urban soils included a shift in pH and increased C and N content compared with forest soil. Studies have shown that the biomass of microfungi and actinomycetes in urban soils was lower than in forest soils and equals 0.12–0.19 mg/g and 0.06–0.44 × 10 −3 mg/g, respectively. Bacterial biomass, on the contrary, increased in urban soils up to 2.6 × 10 –3 – 5.6 × 10 –3 mg/g. The number of ITS gene copies of fungi in urban soils varied from 5.0 × 10 9 to 1.45 × 10 10 copies/g of soil, reaching the highest values in the courtyard. The number of rRNA gene copies of bacteria and archaea in urban soils increased compared with forest soil and amounted to 2.37 × 10 10 – 9.99 × 10 10 and 0.4 × 10 10 – 0.8 × 10 10 copies/g of soil, respectively. In urban soils, morphological changes in microfungi, including the predominance of small spores, were revealed in comparison with forest soils, where mycelium prevailed. An increase in the diversity of microfungi in urban soil and changes in the structure of their communities compared with forest soil was noted. Microfungi found in urban soils are not typical of the background soils of the region and would be expected in more southern conditions. Among them, opportunistic fungi species have been identified in humans, which increases the risk of diseases in residents of the northern region.